Abstract: The tribo -electrochemical behavioo of oxide films on titanium alloy TC4 ( Ti -6AI -4V ) were investigated in 0.9 % NaCI and simulated body fluid by using a translational pin -on -disc friction tester The anode oxide films and micro -arc oxidation coatings were prepared on TC4 and PTFE was used as opposite rubbing materiel The friction coefficient curves were obtained from the tester and the corresponding tribo -electrochemical curves were achieved from a connected three -electrode system The corrosion resistance of micro -arc oxidation coating was found to be about 2 orders of magnitude higher than that of anode oxide film under static state Anode oxide films on TC4 showed better corrosion resistance and lower friction coefficient than that of TC4 substrate The higher the treated voltage was , the lower the friction coefficient Although micro -arc oxidation coatings on TC4 demonstrated a remarkable increase in corrosion resistance , their friction coefficients were higher than that of untreated TC4 The micro -arc oxidation coating treated for 20 minutes showed a better corrosion resistance and frictional performance By comparing the SEM surface morphologies of the worn test pieces , the reasons for high friction of micro -arc oxidation films were analyzed , which was related to the large micro -hole diameter and surface roughness of micro -arc oxidation coating